Giant House Spider
Eratigena atrica
Agelenidae (Funnel-web weavers), Order Araneae. Key family characteristics include three pairs of spinnerets with the posterior pair being noticeably elongated, and building sheet webs that terminate in a funnel-shaped retreat.
Physical Description
Robust body structure with a distinctively elongated, oval-shaped abdomen and a relatively large, dark brown cephalothorax. The body is covered in fine setae (hairs), giving it a velvety appearance rather than a shiny one. Females tend to be larger and heavier-bodied than males.
Size Estimate
Body length typically ranges from 10 to 18 mm for females (males slightly smaller at 12 to 15 mm), with a leg span that can reach up to 45 to 75 mm. This specimen appears to be an adult or sub-adult.
Coloration & Markings
Earthy tones ranging from dark brown to yellowish-brown. The cephalothorax features distinct lighter longitudinal markings or bands. The abdomen is mottled with a complex, yellowish-grey pattern consisting of chevron-like markings and spots down the dorsal side.
Web Type
Builds a large, non-sticky sheet web (funnel web) that extends across a flat surface, often in corners, behind furniture, or in structural crevices, terminating in a tubular retreat where the spider hides.
Eye Arrangement
Eight small eyes of roughly equal size arranged in two slightly curved, transverse rows of four across the front of the cephalothorax.
Leg Characteristics
Long, strong legs covered in visible spines and fine hairs. The legs are generally brown with faint darker banding and are held flat against the surface in a sprawling posture typical of funnel-web weavers.
Venom & Safety Information
Venom Information
Contains neurotoxic venom used primarily to subdue insect prey. While they can deliver a defensive bite if trapped against human skin, their venom is not considered medically significant to humans.
Medical Significance
Harmless to humans. A bite may cause minor, localized pain, redness, or swelling similar to a bee sting, but symptoms typically resolve quickly without medical intervention.
Safety Recommendations
Avoid handling them bare-handed to prevent accidental bites. If found indoors, they can be easily captured using a glass and a piece of cardstock and safely relocated outside.
Habitat & Behavior
Habitat & Range
Native to Europe and introduced to parts of North America (particularly the Pacific Northwest). Prefers dark, undisturbed areas, commonly found in basements, crawlspaces, sheds, garages, and woodpiles.
Behavior & Temperament
Non-aggressive and timid. They prefer to flee when disturbed. They are fast runners when startled. Mostly nocturnal hunters, waiting at the mouth of their funnel retreat for prey to trigger the sheet web.
Diet & Prey
Generalist predators feeding primarily on crawling and flying insects such as flies, cockroaches, beetles, woodlice, and other spiders.
Seasonal Activity
Most commonly seen in late summer and autumn (specifically September and October), when mature males wander extensively in search of females during the mating season.
Description
The Giant House Spider is one of the largest common indoor spiders, known for its impressive leg span and rapid speed. While their large size and sudden movements can startle homeowners, they are beneficial predators that help control household insect populations and pose no threat to humans.
Key Features
Large size, long hairy legs, mottled yellowish-grey chevron pattern on the abdomen, and association with flat sheet webs that end in a funnel retreat.
Similar Species
Tegenaria domestica (Barn Funnel Weaver) which is generally smaller and has more distinct banding on the legs; Eratigena agrestis (Hobo Spider), which requires microscopic examination of genitalia for definitive separation.
Life Cycle
Females produce disc-shaped egg sacs containing dozens to hundreds of eggs in late summer or autumn. Spiderlings hatch the following spring, undergo multiple molts, and reach maturity in one to two years, with a total lifespan of up to two or three years.
Ecological Importance
Acts as an effective natural pest controller in residential and natural environments, helping regulate populations of nuisance insects and recycling nutrients within local food webs.
Conservation Status
Not evaluated by the IUCN, but populations are secure, widespread, and frequently expanding due to human habitation patterns.
Interesting Facts
Despite their intimidating appearance and speed, Giant House Spiders are poor climbers on vertical glass surfaces. They hold a former Guinness World Record for spider running speed, clocking in at over half a meter per second.
Photography Tips
Photograph from a slightly elevated angle to capture the abdominal pattern and leg spination. Use natural light or an off-camera diffuser to reduce harsh reflections, and maintain a calm distance to avoid startling the spider into running away.
Identified: 2026-09-20T21:39:38.206997